Dr. Sandor Demeter
Nuclear Medicine Theranostics - A Game Changer for MB Cancer Patients
I have submitted this article to a number of print news media outlets. I was hoping that they would pick up a "good health news story". As I await some traction from them I thought I would post. it on my blog This is my first article as a freelance health news journalist.
Recent advances in diagnostic and therapeutic Nuclear Medicine promise to improve their quality of life MB cancer patients.
Novel sets of paired diagnostic and therapeutic radiotracers (radiopharmaceuticals) are being developed to detect and treat cancers. The radiotracer has two parts, a radioactive element and a pharmaceutical. By switching the radioactive element, and keeping the same pharmaceutical, the radiotracer can be used to image and subsequently treat patients. This emerging field of linking diagnostic and therapeutic radiotracers is called “theranostics”.
These radiotracers work on a lock and key basis where the radiotracer contains the “key” which selectively binds to tissues and cells which have the “lock.” In this case the tissues of interest are cancer cells. (see graphic at top of page)
The procedure, whether diagnostic or therapeutic, involves injecting a small amount of radiotracer into a vein which is usually administered on an outpatient basis.
Imaging is done on standard Nuclear Medicine PET/CT scanners available in most major urban centres.
In 2019 Health Canada has approved Lutathera marketed in Canada by Advanced Accelerator Applications. Lutathera is approved to treat neuroendocrine tumours (NETs) which have spread, cannot be treated with surgery and are somatostatin receptor-positive.
The radioactive element in Lutathera is Lu 177. Lutathera selectively binds to somatostatin receptors, i.e., the cellular lock. Therapy is achieved by targeted cellular irradiation of cancer deposits.
More recently (2020) Health Canada approved NETSPOT®, also produced by Advanced Accelerator, for the localization of somatostatin receptor-positive NETs. Ga 68 is the radioactive element used in NETSPOT®.
About 20% of patients with NETs have metastatic spread when first diagnosed and the overall ten-year survival is approximately 47%.
Although neuroendocrine tumours (NETs) are rare the number of new cases per year are rising and have doubled over the last approximate 20 years.
Dr. Hambo Zhang, a staff Medical Oncologist at Cancer Care Manitoba (CCMB) with an interest in treating NETs, has noted similar increasing rates of increasing NETs in MB. Although he thinks that the trend may be partially accounted for by increased “incidental” pickup while being imaged for something else (e.g., a CT performed for another reason) the role of yet unknown “environmental causes” can not be entirely ruled out.
Dr. Zhang feels that Lutathera can significantly improve the quality of life for patients with NETs.
Lu 177 based NETs therapy is available in select Canadian centers including Edmonton, Quebec City, Montreal, Toronto, Vancouver, and most recently Winnipeg.
Dr. Piotr Czaykowski, Chief Medical Officer for CCMB, and Dr. Bohdan Bybel, Health Sciences Centre Nuclear Medicine (HSC-NM) Section Head, praised the collaboration between CCMB and HSC-NM in bringing Lutathera to Manitoba.
Prior to Lutathera coming to MB patients could have their diagnostic imaging in Manitoba but about 25 patients had to travel to Edmonton or Quebec City for treatment every year. This resulted in a total of approximately 100 trips as each patient gets up to four therapies.
MB Health covered patients’ transportation and therapy costs, if the latter was not otherwise covered (e.g., under a clinical trial). Patients were responsible for all other costs including accommodation.
The first MB patient was treated with Lutathera at HSC-NM on February 3, 2022. Dr. Zhang expects to treat up to 25 NETs patients a year which will result in up to 100 less trips out of province for MB cancer patients.
Mrs. Stephanie Rossi, Nuclear Medicine Technical Instructor at HSC, shared that there have been no significant challenges to treating patients and all patients have expressed gratitude about not having to travel out of province.
Dr. Bybel feels that theranostic agents are “absolutely a game changer” for what Nuclear Medicine can offer patients and Dr. Czaykowski described Lutathera as the “thin edge of the wedge” as other theranostic agents are on the horizon.
For example, clinical trials are underway for prostate cancer theranostic agents. These radiotracers selectively target the membrane on prostate cancer cells (i.e., prostate specific membrane antigen or PSMA). PSMA can be considered the “lock” and the PSMA radiotracers the “key.”
For PSMA radiotracers the diagnostic radioactive element, Ga 68, can be swapped by a therapeutic radioactive element, say Lu 177, and viola, a new theranostic agent has been added to the diagnostic and treatment toolkit for prostate cancer.
This is exciting news for prostate cancer patients. The Canadian Cancer Society estimates that 24,000 Canadians were diagnosed with prostate cancer in 2021. In Men prostate cancer is the most common diagnosed cancer, and the third most common cause of cancer death.
Nuclear Medicine theranostics is certainly a game changer for cancer patients and MB patients are just starting to see the benefit.